This invention relates generally to railroad cars and to a suspension system for railroad cars. More particularly it relates to a new well car for carrying container freight and to its suspension systems which includes a double axle arrangement for supporting the car on railroad tracks.
Double axle trucks have enjoyed long use in the railroad industry. The typical double axle truck has side frames mounted at the ends of the two axles, bridging the axles. A bolster extends between the centers of the side frames. Coil springs are disposed between the bolster and each side frame. The center of the bolster has a center plate.
The underside of a carbody has a center bearing at each truck location. The truck and carbody are rotatably connected at the underside of the railroad car through the center plate and bearing. The weight of the ca is transferred through the center plate and bearing to the bolster and ultimately through the springs and side frames to the axles and their associated wheels. When the railroad car negotiates a curve, the entire truck rotates with respect to a vertical axis about the center plate and bearing.
Single axle trucks are also known. With such arrangements, a single wheeled axle is provided at each end of the car body. A suspension system, which typically includes leaf springs and swing hangers connected between the underside of the car and the axle, transmits the load to the rail and permits negotiation of curved track sections. One such single axle truck is disclosed in U.S. patent application Ser. No. 733,905, filed May 14, 1985, in the names of Rene H. Brodeur and Boris S. Terlecky and Ronald P. Sellberg and assigned to the assignee of this application. The disclosure of that application is incorporated herein by reference.
Recently, container freight has become a significant revenue source. Freight containers typically have a standard width and height, and a range of lengths. As a result of increased use of containers, a need has arisen to maximize the container loading capacity of railroad cars. To this end, the well car has been utilized in which containers are stacked, one upon the other. Typically, the car contains a well disposed centrally of the car body. The well has no underlying center sill, and thus may be deep and relatively close to the track. Containers may be stacked in the well, and the car may accommodate two stacked containers, each over nine feet high, and yet maintain necessary tunnel clearances. Typically the wells are sized to carry the largest containers which are up to 48 feet in length.
It has been found that the load requirements of double stacked containers, particularly those of 48 feet length, exceed the load carrying capacity of typical single axle trucks. Double axle trucks, such as those previously described, do provide the requisite load carrying capacity. Such trucks, however, are very heavy, and thus adversely affect fuel economy and loading capacity.
Articulated truck arrangements have been employed in which adjacent platforms share a single truck. The attendant disadvantages of articulated platforms are, however, an undesirable aspect of such arrangements. Multiple platforms operate as a unit which requires selective loading procedures. Maintenance and repair requirements also involve removing multiple platforms from service with resultant reduction in revenue.
The present invention is directed to a well car and its suspension systems that is a "stand-alone" platform as opposed to a multiple platform or articulated car It is intended to carry two stacked containers. The car includes the unique suspension system which solves the problems associated with prior known single or double axle truck arrangements for a car of this type and capacity.
The present invention provides a railroad freight car with a double axle suspension system. The car is a stand-alone well car. It includes a central well adapted to receive a pair of containers, one stacked upon the other. The well is depressed to minimize overall height of the loaded car.
The suspension system of the present invention is of the double axle type connected to the car through leaf springs and swing hangers which are pivotally connected to the underside of the carbody and swing longitudinally of the car. The leaf springs are pivotally connected to beams which bridge the ends of adjacent axles. When the car negotiates a curve, the swing hangers pivot. Pivotal movement of the axles with respect to the car to negotiate a curve is accommodated by the relative pivotal movement of the beams and leaf springs and the pivotal action of the swing hangers which permit longitudinal displacement of the carbody relative to the suspension system.
Shear pad assemblies connect the beams to the axles. These shear pad assemblies permit limited angular displacement of the axes of the axles relative to each other. This further facilitates negotiating a curve.
An axle guard frame assembly is rotatably suspended from the underside of the car. It includes vertical axle guards which limit lateral movement of the carbody relative to the axle bearing adapter housings. The axle guard frame assembly and its depending axle guards limit lateral movement of the carbody with respect to the wheels, both in straight and curved sections of track. Its connection to the underside of the car body defines a pivot point for the suspension system.